The phosphoinositide 3-kinases (PI3Ks) belong to a large family of lipid signaling kinases that phosphorylate phosphoinositides at the D3 position of the inositol ring (Cantley, Science, 2002, 296(5573): 1655-7). PI3Ks are divided into three classes (class I, II, and III) according to their structure, regulation and substrate specificity. Class I PI3Ks, which include PI3Kα, PI3Kβ, PI3Kγ, and PI3Kδ, are a family of dual specificity lipid and protein kinases that catalyze the phosphorylation of phosphatidylinosito-4,5-bisphosphate (PIP2) giving rise to phosphatidylinosito-3,4,5-trisphosphate (PIP3). PIP3 functions as a second messenger that controls a number of cellular processes, including growth, survival, adhesion and migration. All four class I PI3K isoforms exist as heterodimers composed of a catalytic subunit (p110) and a tightly associated regulatory subunit that controls their expression, activation, and subcellular localization. PI3Kα, PI3Kβ, and PI3Kδ associate with a regulatory subunit known as p85 and are activated by growth factors and cytokines through a tyrosine kinase-dependent mechanism (Jimenez, et al., J Biol Chem., 2002, 277(44):41556-62) whereas PI3Kγ associates with two regulatory subunits (p101 and p84) and its activation is driven by the activation of G-protein-coupled receptors (Brock, et al., J Cell Biol., 2003, 160(1):89-99). PI3Kα and PI3Kβ are ubiquitously expressed. In contrast, PI3Kγ and PI3Kδ are predominantly expressed in leukocytes (Vanhaesebroeck, et al., Trends Biochem Sci., 2005, 30(4):194-204).
Expression of PI3Kγ is mainly restricted to hematopoietic system, although it can be also detected at lower level in endothelium, heart and brain. PI3Kγ knock-out or kinase dead knock in mice are normal and fertile and do not present any overt adverse phenotypes. Analysis at the cellular level indicates that PI3Kγ is required for GPCR ligand-induced PtdINs (3,4,5)P3 production, chemotaxis and respiratory burst in neutrophils. PI3Kγ-null macrophages and dendritic cell exhibit reduced migration towards various chemoattractants. T-cells deficient in PI3Kγ show impaired cytokine production in response to anti-CD3 or Con A stimulation. PI3Kγ working downstream of adenosine A3A receptor is critical for sustained degranulation of mast cells induced by FCεRI cross-linking with IgE. PI3Kγ is also essential for survival of eosinophils (Ruckle et al., Nat. Rev. Drug Discovery, 2006, 5, 903-918).
Given its unique expression pattern and cellular functions, the potential role of PI3Kγ in various autoimmune and inflammatory disease models has been investigated with genetic and pharmacological tools. In asthma and allergy models, PI3Kγ−/− mice or mice treated with PI3Kγ inhibitor showed a defective capacity to mount contact hypersensitivity and delayed-type hypersensitivity reactions. In these models, PI3Kγ was shown to be important for recruitment of neutrophils and eosinopohils to airways and degranulation of mast cells (see e.g. Laffargue et al., Immunity, 2002, 16, 441-451; Prete et al., The EMBO Journal, 2004, 23, 3505-3515; Pinho et al., L. Leukocyte Biology, 2005, 77, 800-810; Thomas et al., Eur. J Immunol. 2005, 35, 1283-1291; Doukas et al., J. Pharmacol. Exp Ther. 2009, 328, 758-765).
In two different acute pancreatitis models, genetic ablation of PI3Kγ significantly reduced the extent of acinar cell injury/necrosis and neutrophil infiltration without any impact on secretive function of isolated pancreatic acini (Lupia et al., Am. J. Pathology, 2004, 165, 2003-2011). PI3Kγ−/− mice were largely protected in four different models of rheumatoid arthritis (CIA, α-CII-IA, K/BxN serum transfer and TNF transgenic) and PI3Kγ inhibition suppressed the progression of joint inflammation and damage in the CIA and α-CII-IA models (see e.g., Camps et al., Nat. Medicine, 2005, 11, 939-943; Randis et al., Eur. J. Immunol, 2008, 38, 1215-1224; Hayer et al., FASB J., 2009, 4288-4298). In the MRL-lpr mouse model of human systemic lupus erythematous, inhibition of PI3Kγ reduced glomerulonephritis and prolonged life span (Barber et al., Nat. Medicine, 2005, 9, 933-935).
There is evidence suggesting that chronic inflammation due to infiltration by myeloid-derived cells is a key component in the progression of neurodegeneration diseases, such as Alzheimer's disease (AD) (Giri et al., Am. J. Physiol. Cell Physiol., 2005, 289, C264-C276; El Khoury et al., Nat. Med., 2007, 13, 432-438). In line with this suggestion, PI3Kγ inhibition was shown to attenuate Aβ(1-40)-induced accumulation of activated astrocytes and microglia in the hippocampus and prevent the peptide-induced congnitive deficits and synaptic dysfunction in a mouse model of AD (Passos et al., Brain Behav. Immun. 2010, 24, 493-501). PI3Kγ deficiency or inhibition also was shown to delay onset and alleviate symptoms in experimental autoimmune encephalomyelitis in mice, a mouse model of human multiple sclerosis, which is another form of neurodegeneration disease (see e.g., Rodrigues et al., J. Neuroimmunol. 2010, 222, 90-94; Berod et al., Euro. J Immunol. 2011, 41, 833-844; Comerford et al., PLOS one, 2012, 7, e45095; Li et al., Neuroscience, 2013, 253, 89-99).
Chronic inflammation has been formally recognized as one of the hallmarks for many different types of cancers. Accordingly, selective anti-inflammatory drugs represent a novel class of anti-cancer therapies (Hanahan and Weinberg, Cell, 2011, 144, 646-674). Since PI3Kγ is reported to mediate various inflammatory processes, its role as an immune oncology target has also been investigated. A recent study reported that PI3Kγ deficiency suppressed tumor growth in the syngeneic models of lung cancer, pancreatic cancer and melanoma (LLC, PAN02 and B16). PI3Kγ deficiency or inhibition also inhibited tumor growth in a spontaneous breast cancer model (Schmid et al., Cancer Cell, 2011, 19, 715-727). A further study reported that PI3Kγ deficiency could ameliorate inflammation and tumor growth in mice having colitis-associated colon cancer, (Gonzalez-Garcia et al., Gastroenterology, 2010, 138, 1373-1384). Detailed mechanistic analysis indicates that tumor infiltration by CD11b+ myeloid cells can cause protumorigenic inflammation at tumor sites and PI3Kγ in the myeloid cells is critical in mediating signaling of various chemoattractants in bring the cells to the tumor (Schmid et al., Cancer Cell, 2011, 19, 715-727). Other studies suggest that PI3Kγ is also required for differentiation of naïve myeloid cells into M2 macrophges at tumor sites. M2 macrophages promote tumor growth and progression by secreting immunosuppressive factors such arginase 1, which depletes the tumor microenvironment of arginine, thereby promoting T-cell death and NK cell inhibition (Schmidt et al., Cancer Res. 2012, 72 (Suppl 1: Abstract, 411; Kaneda et al., Cancer Res., 74 (Suppl 19: Abstact 3650)).
In addition to its potential role in promoting protumorigenic microenvironment, PI3Kγ may play a direct role in cancer cells. PI3Kγ is reported to be required for signaling from the Kaposi's sarcoma-associated herpevirus encoded vGPCR oncogene and tumor growth in a mouse model of sarcoma (Martin et al., Cancer Cell, 2011, 19, 805-813). PI3Kγ was also suggested to be required for growth of T-ALL (Subramanjam et al., Cancer Cell, 2012, 21, 459-472), PDAC and HCC cells (Falasca and Maffucci, Frontiers in Physiology, 2014, 5, 1-10). Moreover, in a survey of driver mutations in pancreatic cancer, PI3Kγ gene was found to contain second highest scoring predicted driven mutation (R839C) among the set of genes not previously identified as a driver in pancreatic cancer (Carter et al., Cancer Biol. Ther. 2010, 10, 582-587).
Finally, PI3Kγ deficiency also has been reported to offer protection to experimental animals in different cardiovascular disease models. For examples, lack of PI3Kγ would reduce angiotension-evoked smooth muscle contraction and, therefore, protect mice from angiotension-induced hypertension (Vecchione et al., J. Exp. Med. 2005, 201, 1217-1228). In rigorous animal myocardial infarction models, PI3Kγ inhibition provided potent cardioprotection, reducing infarct development and preserving myocardial function (Doukas et al., Proc. Natl. Acad. Sci. USA, 2006, 103, 19866-19871).
For these reasons, there is a need to develop new PI3Kγ inhibitors that can be used for the treatment of diseases such as cancer, autoimmune disorders, and inflammatory and cardiac diseases. This application is directed to this need and others.